METHOD FOR THE PRECIPITATION OF NICKEL

摘要

A method (10) for the recovery of nickel and cobalt from leach solutions in the presence of iron and/or chrome, the method comprising the steps of: i) adding a reductant (13) to a leach solution containing nickel, cobalt and iron, such that any iron present as ferric sulphate is reduced to ferrous sulphate and/or any hexavalent chrome is reduced to trivalent chrome; ii) neutralising (14) at least a portion of the free acid through addition of a neutralising agent; iii) further addition of the reducing agent (15) to ensure all iron present remains in the ferrous form and/or any chrome remains in the trivalent form; iv) heating the solution prior to mixed sulphide precipitation; v) adding a mixed sulphide seed (21) and hydrogen sulphide (22) to effect precipitation (20) of the nickel and cobalt in the form of a mixed sulphide product (24); and vi) maintaining this mixture in the presence of hydrogen sulphide (22) for the required residence time to effect complete precipitation of the mixed sulphide product (24).